In LTE based cellular systems various synchronization signals including, e.g., primary synchronization signal/secondary synchronization signal (PSS/SSS) and a broadcast channel (BCH) signal are transmitted at a fixed position in frequency and time in a frame. These signals are important for a user equipment (UE) device to start decoding information from an eNode B (eNB). Since PSS/SSS and BCH signals are the very first pieces of system information that a UE device seeks to acquire, their location relative to the structure of the frame cannot be changed.
Consider a dense and unplanned deployment of LTE small cells, e.g., femto cells, in a single frequency band. If the small cells are synchronous at the frame level, then the synchronization signals, (PSS/SSS) and BCH channel signals, of the small cells may collide with each other. This tends to increase interference to a UE device that is trying to detect the small cells. One easy solution can be that the small cells be asynchronous. This solves the problem of BCH and PSS/SSS collisions. However, this approach makes inter cell interference coordination methods, e.g., enhanced inter-cell interference coordination (eICIC), schemes ineffective since the devices act asynchronously.
Based on the above discussion, there is a need for new methods and apparatus to control interference when small cells, e.g., femto cells, are to be operated using a single common frequency band. It would be beneficial if at least some new methods and apparatus decreased interference with regard to detecting some important control signals being transmitted by adjacent base stations yet provided for some level of common synchronization so that inter-cell interference coordination (ICIC) schemes and/or other interference management can still be effective.